Vulcanizing rubber



' 919 patented Au 21,1923

Patented Oct. 27, 1925.

UNIT D STATE S PATENT Lossce.

enoncn n. scams, or was, mew messy.

vnncamamo auan'im.

Ho Drawln'g'.

of rubber, and has for its object the utilization of new products that are mentioned for this purpose. If 1 I The use of giiganic nitrogenous compounds in' the canization of rubber is quite general and the products so usedfiare technically'lerme'd' accelerators.

Whether sucli bodies'act as catalysts,'sulphur carriers, 'polymerizers, "activators, qr

accelerators, is not. the pur ipse ofi this speci;

fication todiscuss, but i me e use'fof the conventional term accelerator in mymention ofthem. '1 In experimental work with various nitrogenous organic bodies that I haye used, -.to assist in the vulcanization of rubber, I have found that certain derivatives of carbodiimides form: exceedingl valuable products for this purpose, an contrary to the general impression that they are not'suitable for use inrubber vulcanization.

In a previous-patent application No. 899,-

No. 1,465'743 I have mentioned tetra henylmelaminetetraihenyltricarhodiimi e),- G,,H ,,N,= ,H, .115) iN, a phenlyiated carbodiimide as an accelerator, and-I ve also found that other derivatives 'ofiearbodiimides are also yery eflicient aids torrulcanization, and especially where they are markedly basic in character.

An exampleofsuch a roduct te tratolylmelamine, tetratoly tricarbodnmide) expressed by the ollowing formula:

Ca cun 1 o I product has a nitro en content of over 17% and is comparativ y stable during the period and at the usual temperatures of vulcanization.

" The product can be produced in various ways, but one manner is to unite 2 molecules pf'carhotolylimide QHJT; with l molecule Application me new, 1923. sum in. 647,785.

of carboditolylimiddb-,H',N: C lTQH?) pro- .ducing 1 molecule of tetratolyltrica'r diiwide. The same molecular percentages of the polymeric forms res eotively', of these same carbo-tolylimides,a produce a tetratolyltricarbodiunide. This identifies the product then as a derivative of carbodiimi'de.

i ii}.

A similar product, resultsfrom the correspondin umon ofq2-molecules of carboxylilimi e C,H,',,N,' with 1 molecule of carbodixylilimide CJLN: G: NC H which then would be tetragliltricarbodiimide O,,H,,N-,=C,H,(C Ho 5. This body also proves a goodacce erator but with a some what'lower nitrogen content.

One method of obtaining the carbo- (mono ."or (ii substituted) imides, is by desulphurizing the corresponding substituted thioureas. Such desnlp urizin is however subject to man modifications, epending on the i'esence 0 other pro ucts may result. v

For ,instanceanustard oil is -frequentl Y present in disubstituted thiourea. If desu products,'and so mixed phurizationof di-substituted thiourea takes place then in the presence of ammonia and 'mustard'oil, a formation of the corresponding mono-substituted thiourea could take place, and a desulphurization of both thioureas would then yield thetwo correspond.

in cube-substituted imides.

e'se oarbo-imides then might be combined to. tetra-substituted tricarbodiimide,

eventhou h intermediate roducts form du'r' suc combination. (are are also seve othermethods available tor the production of theseproducts:

Tetratolyltricarbodiimide seems to be of such stable characterthat it can be used even in a very impure state and still give excellent results; It is'c ptocrystallme and so its isolation in a regldar crystalline form is efi'ected with some difliculty, hutit is entirely unnecessary that it be pnepared of this de of purity'foruseiso item be used,

.eit er in'its amorphouso'rg'umm state, or

i, mixed isomeric form' or with its related by-products and im urit es present, without materially diminishmg its Merely its degree of urity should be determined and then formu ac for its use would be based on such pure content.

This accelerator roves itself of unusual value in tire and tube compounds.

An example of a representative rubber compoundand its cure, using a tetratolyltricarbodiimide as an accelerator would be;

For high tensile black.

For friction stock.

82% smoked sheets.

5% sulphur. 2% magnesium oxide. 10 76 zmc oxide. 7

0 &% tetratolyltricarbodiimi'de.

ure: 35 minutes at 37 lbs. steam pressure.

For red tube stock.

(SW/ smoked sheets. 18% golden or crimson antimony.

5% zinc oxide.'

7% barytes. 0 96 tetratolyltricarbodilmide.

Many of the derivatives of carbodiimides are c 'to-crystalline compounds with the amorp ous appearance more frequently in evidence than the crystalline form, and so they are not readily se arated from their accompanyin compoun s, that may be present due to tieir origin,'=or present as byproducts of their formation. Carbodiimide as well as the phenyl, tolyl and xylihsubstitution products thereof, may some of them, assume the form of' polymeric modifications.

The use of the term cryptocrystalline in this specification is intended to designate abody that is at times amorphous;either in factor in a pearance, and yet at other times is'of a de nite crystalline form.- Hidden crystals would be a concise definition.

These cryptocrystalline carbodiimide derivatives seem to be generally of great stability at the temperatures required for v'ulcanization, have a fairly high nitrogen content, and appear not to be very reactive with their own byproducts during use.

Another characteristic of them is, that frequently they are highcrnuelting bodies, resulti from the decomposition of lower melting bodics, which in acceleration means,

the original accelerator of lower ..melti'n,c r point s rogressively decom 'd under vulcanlzation intohe lower 'melt less exhaust pleted, the higher melting accelerator becomes more or further vulcanization in the cold,'or as ex pressed in technical parlance, the resultant rubber stands aging better.

rubber vulcanization, the bodies herein men tioned and which appear to have superipr qualities to many of the compounding m product thus has, better aging 'quahtres or My invention then consists in utilizing, in.

gredients used heretofore in compoundingand vulcanizing rubber.

While I have described my invention in detail, and stated the manner in which the products mentioned may be prepared and used, it is to be understood that Ido not mean to be limited in this specification to the use of the particular ingredients mentioned as examples, or in any way, exce t by the claims as set forth and annexed erewitll." It is further to be understood that my in; vention is not to be construed as dependent on the accuracy or soundness of any of the theories herein expressed, or on the correct ness of the structural formulas used to'designate the products.

Havin no'w described my invention and havin s own in what manner the same may be utfiized, what Iclaim as new, and desire to secure by Letters Patent is; 1. A process of vulcanizing rubber which consists in, incorporating a vulcanizing agent with rubber, ,then under heat, accelerating vulcanizatifl'n the use" of tetratolyltricarbodiimide'ih the rubber mix ture.

2. A process'of vuldanizing' rubber which consists in, -incorporating bodiimide,-either by itself' or in com ination with another organic solid, into rubberas an aid to vulcanization, then heatin the resultant rubber mixture with a yulcanrzing agent to effect vulcanization. i

3. A process of'vulcanizing rubber which consists in, incorporating a vulcanizing agent with compounded-rubber, then underheat, causing the formation oftetratolyltricarbodiimide within the rubber mixture while effecting vulcanization. z

4. In the vulcanization of rubber the combination of: sulphur or a suitable compound .of s'ulphury as a vulcanizing agent; tetratolyltrirarbodiimide either by itself or. in

combination with other bodies,-as .an aid to VjllCllfllZlllZlOllI raw or com ounded rubber,as the product to be vu camzed; and

means applied to these materials when united, to efl'ect vulcanization.

5. A process of vulcanizing rubber which consists in modif 'ng the melting point of tetratolyltrlcarbo iimlde throu h combination with another organic soli m that itmay be used as an accelerator, then incor porating the accelerator thus formed into rubber,- then heating the re 'ultii ht rubber mixture with a vulcanizing ngcht to effect. vulcanization; 6. .A process of vulcenizing rubber which.-

consists in, incorporating into rubber .an acoelerator resulting from [combination of desul hurized money and ditolylthiourea, then. \eating the resultant rubber mixture with a vulcanizing agent to effect vulcanization.

- ing the resultant rubber mixture with a vulcanizing. agent to effect vulcanization.

8. A process of vulcamzmg rubber which COIlSlSlS an, lllCOI'POliltlfl! Into rubber an 7. A process of vulcanizing rubber which accelerator resulting from a combination of carborlitolylimide and carbomonotolylimide,

or of their polymeric modifications res cctivcly, then heating the resultant ru bc'r mixture with vulcanizing agent to effect vulcanization.

9. A v vulcanized a inbound, containing rubber or similar material, a vulcanizing agent, and ,tetratolyltricerbodiimide.

10.A vulcanized compound, containing rubber or similar materlal, a vulcunizing agent, and a combination of desulphurizvd monoand rlitolylthiourea.

11. A vulcanized comPound, containing rubber or similar material, a vulcanizing agent, and a glitolflthiourca that has been desulphurizcd in the presence of tolyl mustard oil and ammonia.

12. A vulcanized compound, containing rubber or similar material, a v'ulcanizing agent, and a combination of cnrbomonoand carbmli-toiylimirlc, or of their polymeric modifications respectively.

GEORGE H. STEVENS.

the melting point of consists in, modif ing h b eom matetratolyltrieerbo iimlde throu tion with another organic soli may be used as an accelerator, then incorporating the accelerator thus, formed into rubber, then heating the resultant rubber mixture with a vulcanizing agent to effect vulcanization.

6. A process of vulcanizing rubber which consists in, incorporuting into rubber an accelerator resulting from acombinetion of dcsulphurized monqand ditolylthiourea, then heating the resultant rubber mixture with a vulcenizing agent to effect vulcanization.

7. A process of vulcanizing rubber whichconsists in, incorporating mto rubber an accelerator resulting from a rlitolyltblourea that has been (lesulphurized in the presence of tolyl mustard oil and ammonia, then beating the resultant rubber mixture with a, vulcanizing agent to effect vulcanization.

8. A process of vulcanizmg rubber which consists in, incorporation into rubber on m that it accelerator resulting from a combination of curborlitolylimirlc and carbomonotolylimide, or of their polymeric modifications resgnectively, then heating the resultant ru bcr mixture with u vulcnnizing agent to effect vulcanization.

9. A vulcanized compound, containing rubber or similar material, a vulennizing agent, and ,tetrutolyltricarbodiimide.

A vulcanized compound, contulnmg Certificate of Correction.

It is hercbycertified that in Letters Patent No. 1,559,196, ranted October 2?, 1926, upon the up lication of George H. Stevens, of Newark, .r ewJersey, for an nnprovement in i ulcanizing Rubber, an error ap'pcars in theprinted specification requiring correction as follows: Page 1, line 70, in the erl'ua'tion, figures 53 read 36; and that the said s for the inferior Letters Patent iould be read with this correct ion therein that the same may conform to the record of the case in the Patent Uiiice.

Signed and sealed this 19tlrday of January, A. D. 1926.

[emu] WM. A, KINNAN, Acting Commissioner of Patents.

Certificate of Correction.

It is hereby certified that in Letters Patent No. 1,559,196, granted October 2?, .925, upon the up lication of George H. Stevens, of Newark, New Jersey, for an w-pmvement in uicanizing Rubber, an error appears in the printed specification requiring correction as follows: Page 1, line 70, in the 'uation, for the inferior hgmm 53 read 35; and that the said Letters Patent 5 muid be read with this mnwtiun therein that the same may conform to the record nf the case in the Patent ()Iiieu.

Signed and sealed this 19th day of January, A. D. 1926.

WM. A. KINNAN,

[sank] Acting Commissioner 0/ Patents. 

